as mentioned in the previous tags, it's pretty present throughout the games as well. morrigan especially is a pretty stereotypical "ice queen" archetype who can be "softened" (for lack of a better word) by her romantic relationship with a male character to some extent (this "softening" does not solely occur inside a romance or with a male warden tbc, but the romance frames the same events very weirdly and is also very... transactional?) she is incredibly sexualized and her entire romance is frankly heterosexual and plays into gender roles to an unbelievable degree. some of the shit you can say to her while still having a good relationship with her boggles the mind—iirc you can just outright call her a bitch. a lot of the early/mid romance especially treats her as a sexual object. and as others have touched on, she and her writing get hit hard in general with the whore part of the madonna/whore complex. a lot of misogyny with morrigan is also little things scattered throughout as well that are harder to bring up as examples off the top of my head.
cassandra gets framed oddly as well. in many ways her "masculine" role as a blunt warrior feels as if gaider is trying to "make up" for it with her love of romance and wish to be courted. he also wrote fiona, both in the novels and in-game, and was the one who decided that the headstrong former slave who started a rebellion would sell all her people into slavery and do nothing in IHW. which i truly just have nothing to say about beyond that because what the hell?
gaider's misogyny is also present in his writing of his male characters (or more accurately, in the women surrounding his male characters)—think how in alistair's backstory/quest the women around him get framed as shrill and oppose him for very "petty" reasons. isolde is portrayed as stupid and overtly emotional (she is notably the only one who actually cries during the redcliffe castle portion of the quest, including the child you can kill) in comparison with her male counterparts, teagan and eamon. and goldanna is. well, first of all, she's named goldanna which is clearly a play on "gold digger" and she gets incredibly unsympathetic framing for not wanting a relationship with alistair, before she is promptly dismissed. none of this is to say that everything about how these two treat him is alright, but male characters who oppose/manipulate him (like, say, eamon) don't get villainized in the same way, and even when they are outright villains, they get much more respect than the female characters are shown (loghain).
and in zevran's backstory he quite cruelly murdered his female lover and we, as a player, are primarily intended to have sympathy for him.
gaider is also responsible for the writing of the human noble origin, where if you play a female cousland, you are berated for not being more feminine and trying to get married to a man while eleanor talks about how it was the "softer pursuits" that earned her a husband (which later canon also reveals as just straight up not true lmao).
there's also broader phenomenon across the games he's responsible for as the head writer who okayed some of this, even if he wasn't directly involved in those writing decisions and didn't have absolute control over everything himself—as an example @thewardenisonthecase pointed out recently that, across every single dlc and origins itself, and including temporary companions, there are only three female warrior companions and two out of those three die. and then in the later two games he worked on we only get two more. total. in comparison, there are at least seven male warriors across the first three games, and i know i'm missing some, if only because i did not count any dlc or temporary characters.